Rubus trivialis; Variety xe2x80x98Clark Goldxe2x80x99.
This new variety named xe2x80x98Clark Goldxe2x80x99 is the result of a spontaneous mutation of the southern dewberry, Rubus trivialis, a wild blackberry species, and was discovered on cultivated land in south Texas (Jackson County). The plants of the new variety lack anthocyanin pigment throughout all tissues, including the fruit, which is yellow at maturity, unlike the dark purple fruit of normal blackberries. This variety like most blackberry cultivars has biennial canes with a dormant period between first year canes primocanes) and second year canes (floricanes) prior to flowering and fruiting. This new variety is analogous to xe2x80x98Kiwigoldxe2x80x99, U.S. Plant Pat. No. 11,313, a yellow-fruited mutation of the red raspberry variety xe2x80x98Heritagexe2x80x99, although occurring in a blackberry species rather than a raspberry species.
Blackberry and raspberry species belong to the same genus Rubus, but fall within different subgenera. The distinguishing morphological difference between blackberries and raspberries is evident when the fruit is picked. In the blackberry the central receptacle (torus) of the fruit remains intact with the fruit when picked, whereas in the raspberry the torus remains attached to the stem resulting in a fruit with a hollow core. In this respect, xe2x80x98Clark Goldxe2x80x99 is a typical blackberry fruit with a solid core when picked. There are commercial raspberry varieties available with yellow fruit, as well as those with red or black fruit. To date there are no commercial varieties of blackberry with yellow fruit.
This new cultivar is intended to be marketed as a novel blackberry variety for home and commercial blackberry fruit production. The fruit in turn can be used for fresh eating or as processed fruit or juice. This variety could also be used as a parent in a plant breeding program to transfer the yellow fruit character and the associated lack of anthocyanin to other blackberry cultivars. The absence of anthocyanin is, in effect, a gene marker for the yellow fruit character and will facilitate selection for yellow fruit in a hybridization program. The absence of anthocyanin can be detected at a very early stage of the primocane (first year) while the yellow fruit color is not evident until maturity of the fruit in the floricane (second year).
The present invention relates to a new and distinct variety of blackberry plant having a yellow fruit and lacking anthocyanin in its various plant parts. This new variety also has double flowers and large, elongated sepals which distinguish it from the wild dewberry, Rubus trivialis, from which it derives. The original plant was a naturally occurring whole plant mutation found in a fencerow along County Road 476 in Jackson County, Tex. The fencerow was bordering a cultivated field, which had been planted at various times to different crops including pasture grasses, grain sorghum and various varieties of blackberries.
The original plant of the new variety was propagated asexually by tip layering in 2000 and 2001. All new plants were phenotypically stable for yellow fruit and the absence of anthocyanin. The asexual reproduction occurred at the same location in Jackson County, Tex.
This new variety has not been observed under environmental conditions outside of southern Texas. The phenotype may vary considerably in other environments, particularly in more northerly climes, although the yellow fruit color and absence of anthocyanin should not be affected.
The new cultivar xe2x80x98Clark Goldxe2x80x99 has three distinctive characteristics which distinguish it from its progenitor, the southern dewberry, Rubus trivialis, and other blackberry varieties. One of these is major and readily visible (yellow fruit and yellow green plant), while the other two are variations in the floral structure. xe2x80x98Clark Goldxe2x80x99 is a spontaneous genetic mutation in which normal anthocyanin pigmentation is suppressed, resulting in vegetative tissues which lack red and purple pigments, and in the fruit which is yellow at maturity. The absence of anthocyanin and the yellow fruit are presumed to be different expressions in the vegetative and fruit tissues, respectively, of the same genetic trait-ie. suppressed anthocyanin production. The variations in the floral structure of the new variety are 1) double flower which has an increase in the number of petals over the normal corolla complement of five and 2) larger and elongated sepals as compared to the normal calyx. The petals of the new variety are also larger, which combined with the increased petal number, give the flower a fuller appearance, thus the term xe2x80x9cdouble flowerxe2x80x9d. These floral abnormalities appear to be genetic traits and not symptoms of the Rosette disease, also known as xe2x80x9cdouble blossomxe2x80x9d, caused by the fungal pathogen Cercosperella rubi, because xe2x80x98Clark Goldxe2x80x99 flowers produced fruit of normal size and drupelet number unlike Rosette flowers which are sterile.
Like the wild dewberry, Rubus trivialis, from which it derives xe2x80x98Clark Goldxe2x80x99 is a trailing vine with numerous curved thorns on the canes, petioles and petiolules. The wild dewberry (WDB) has normal anthocyanin coloration which shows in nearly all its plant tissues as a reddish tinge of varying intensity in the canes, leaves, petioles, petiolules and thorns. By contrast, xe2x80x98Clark Goldxe2x80x99 plants lack anthocyanin and its vegetation is a light green color to yellow green color with no trace of red coloration. The primocanes of xe2x80x98Clark Goldxe2x80x99 are in the Yellow Green Group (146C) of The Royal Horticultural Society Colour Chart while WDB primocanes are in the Red Purple Group (59A). Anthocyanin coloration in normal plants is especially pronounced in winter foliage, and around leaf margins, at the base of petioles and in damaged plant tissues. The fruit of normal blackberries turn from green to bright red to dark purple or xe2x80x9cblackxe2x80x9d at maturity. xe2x80x98Clark Goldxe2x80x99 berries are dark green when immature and turn to yellow, Yellow Group (12B) as they ripen without passing through the red berry stage.
Rubus trivialis, like most blackberry cultivars, has the normal corolla complement of 5 petals, which are discrete and spatulate (club-shaped). In contrast, xe2x80x98Clark Goldxe2x80x99 flowers usually have 6 or more petals, and as many as 15 petals. The petals are also larger, fan-shaped and overlapping. Normal blackberry flowers also have a small calyx with 5 sepals. xe2x80x98Clark Goldxe2x80x99 flowers have a larger calyx with elongated sepals. In all other aspects xe2x80x98Clark Goldxe2x80x99 is morphologically identical to its progenitor, Rubus trivialis, including fruit characteristics such as size, shape, pH (3.26) and soluble solids (8.7%).